Self-organization of spindle-like microtubule structures
Self-organization of spindle-like microtubule structures
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DOI：
10.1039/c8sm01835a
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发表时间：
2019-06-28
期刊：
影响因子：
3.4
通讯作者：
Ross, Jennifer L.
中科院分区：
文献类型：
--
作者：
Edozie, Bianca;Sahu, Sumon;Ross, Jennifer L.
微管自组织是一个重要的物理过程，是细胞分裂等几种基本功能的基础。在细胞分裂中，主要的排列方式是有丝分裂纺锤体，这是一种基于微管的足球状机器，负责分离染色体。我们感兴趣的是纺锤形自组织背后的基本原理。先前的生物学工作假设马达蛋白控制纺锤体的正确形成。这些马达蛋白中的许多也是微管交联剂，因此尚不清楚关键方面是马达活性还是交联。在这项研究中，我们试图解决这个问题，通过检查使用交联剂单独的微管的自组织。我们使用一个最小的系统组成的微管蛋白，一个反平行的微管交联蛋白，和拥挤剂探索相空间的组织作为微管蛋白和交联剂浓度的函数。我们发现，浓度的反平行交联剂，MAP65，有一个显着的影响组织，并导致在相对较低的浓度，而不需要运动活动的纺锤状安排。令人惊讶的是，微管的长度仅适度影响平衡相。我们表征这些纺锤状组织的形状和动态。我们发现它们是双折射均匀类晶。微管具有缓慢的流动性，但交联剂在类触体内具有快速的流动性。这些结构代表了微管自组织纺锤体重演的第一步，可用作与细胞分裂生物过程相关的进一步生物物理和活性物质研究的初始结构。
Microtubule self-organization is an essential physical process underlying several essential cellular functions, including cell division. In cell division, the dominant arrangement is the mitotic spindle, a football-shaped microtubule-based machine responsible for separating the chromosomes. We are interested in the underlying fundamental principles behind the self-organization of the spindle shape. Prior biological works have hypothesized that motor proteins control the proper formation of the spindle. Many of these motor proteins are also microtubule-crosslinkers, so it is unclear if the critical aspect is the motor activity or the crosslinking. In this study, we seek to address this question by examining the self-organization of microtubules using crosslinkers alone. We use a minimal system composed of tubulin, an antiparallel microtubule-crosslinking protein, and a crowding agent to explore the phase space of organizations as a function of tubulin and crosslinker concentration. We find that the concentration of the antiparallel crosslinker, MAP65, has a significant effect on the organization and resulted in spindle-like arrangements at relatively low concentration without the need for motor activity. Surprisingly, the length of the microtubules only moderately affects the equilibrium phase. We characterize both the shape and dynamics of these spindle-like organizations. We find that they are birefringent homogeneous tactoids. The microtubules have slow mobility, but the crosslinkers have fast mobility within the tactoids. These structures represent a first step in the recapitulation of self-organized spindles of microtubules that can be used as initial structures for further biophysical and active matter studies relevant to the biological process of cell division.